n6 THE POPULAR SCIENCE MONTHLY. 



subject. From what knowledge I have been able to obtain in that 

 department, I am inclined to arrange the secondary class thus: 

 Breccia, compact, or shell limestone; gypsum, secondary sand- 

 stone. I leave much, also, for peculiar local formations. A gen- 

 tleman presented specimens to the Troy Lyceum, from Illinois, of 

 gypsum and secondary sandstone, and informed me that the latter 

 overlaid the former in regular structure. Myron Holly and others 

 have given me similar specimens, which they represent as being 

 similarly situated, from localities in the western part of this State. 

 This secondary sandstone is sometimes more or less calcareous. I 

 believe it is used for a cement by the canal company, which hardens 

 under water. Will you do me the favor to settle this question ? 

 On your way to Detroit you may perhaps, without material in- 

 convenience, collect facts of importance to me in reference to sec- 

 ondary and alluvial formations. Anything transmitted to me 

 by the middle of April on these subjects will be in season, because 

 I shall not have printed all the transition part before that time. 

 Have you any knowledge of the strata constituting Rocky Moun- 

 tains ? Is it primitive, or is it gray wacke, like Catskill Mountains ? 

 I have said in a note that after you and Dr. E. James set foot upon 

 it we shall no longer be ignorant of it. I intend to kindle a blaze 

 of geological zeal before you return. I have adapted the style of 

 my index to the capacity of ladies, plow-joggers, and mechanics." 

 Prof. Eaton also delivered lectures at Lenox Academy and the 

 Medical College at Castleton, Vt., where he was appointed Pro- 

 fessor of Natural History in 1820. He gave lectures and practical 

 instructions in Troy, and thus laid the foundation for the estab- 

 lishment there, as a direct result of his work, of the Lyceum of 

 Natural History ; and it is said that in the fall of 1818 Troy could 

 boast of a more extensive collection of American geological speci- 

 mens than could be found at any other literary institution in this 

 country. The geological and agricultural survey of Albany and 

 Rensselaer Counties, made in 1820 and 1821, by Prof. Eaton and 

 Drs. T. Romeyn and Lewis C. Beck, at the expense of the Hon. 

 Stephen Van Rensselaer, is believed to have been the beginning 

 of such surveys in this country, and was described by Prof. Silli- 

 man, in his Journal, as a novel attempt. Next was a geological 

 survey by Prof. Eaton, also at the instance of Mr. Van Rensselaer, 

 of the district adjoining the Erie Canal, the result of which was 

 published in 1824, in a report of one hundred and sixty pages, with 

 a profile section of rock formations, from the Atlantic Ocean, 

 across Massachusetts and New York, to Lake Erie. Governor 

 Seward said of this work, in the Introduction to the Natural His- 

 tory of the State of New York, that it " marked an era in the 

 progress of geology in this country. It is in some respects inac- 

 curate, but it must be remembered that its talented and indefati- 



